Vacuum distillates seen under a totally new light

The use of high-temperature two-dimensional gas chromatography led to strong advances in the analysis of hydrocarbons in vacuum distillates. To provide sufficient analytical details, IFPEN recently improve 3D representation by adding an online Supercritical Fluid Chromatography separation dimension to high-temperature two-dimensional gas chromatography.

Marion Courtiade Physics and analysis Division marion.courtiade@ifpen.fr	Thomas Dutriez Physics and analysis Division

In order to meet the increasing energy demand in a context of expected cap on fossil fuel availability, it is essential to convert as much petroleum as possible into fuels. Vacuum distillates conversion processes play a major role in achieving this goal but require detailed analytical data for their optimization via kinetic modeling.

Although detailed molecular information is available for lighter cuts such as gasoline or diesel cuts, few structural information is available for vacuum distillates, due mainly to the number of Components they contain (over a million).

Recently, the use of high-temperature two-dimensional gas chromatography (HT-2D-GC) led to strong advances in the analysis of hydrocarbons in vacuum distillates. However, two separation dimensions did not provide sufficient analytical details.

Improvement of the separation power of this technique was performed at IFPEN by adding an online Supercritical Fluid Chromatography separation (SFC) dimension, which allows the pre-fractionation of compounds according to their chemical family. Its hyphenation to HT-2D-GC resulted in unprecedented analytical details on vacuum distillates and a 3D representation of the hydro-carbons distribution was proposed. This kind of analytical tools proves to be of major importance for the study of conversion processes but may also be extended to the analysis of other complex matrices, such as those produced in biomass transformation processes.

3D chromatograms produced by analysis of a vacuum distillate by SFC / GC2D-HT coupling.

Publications

• T. Dutriez, M. Courtiade, D. Thiébaut, H. Dulot, F. Bertoncini, J. Vial, et al., HT-2D-GC of hydrocarbons up to nC (60) for analysis of vacuum gas oils, J. Chrom. A, 1216, (2009) p.2905-2912. DOI : 10.1016/j.chroma. 2008.11.065
• T. Dutriez, M. Courtiade, D. Thiébaut, H. Dulot, F. Bertoncini, et al., Extended characterization of a vacuum gas oil by offline LC-HT-2D-GC, J. Sep. Sci., 33 (2010) p.1787-1796. DOI : 10.1002/jssc.201000102

>> See also IFPEN Publications database